No voltage to coil….

[Spandangler]

Hey folks.
This frickin Bally Corvette has fought me at every turn.
After 4 years, I reunited the cab and playfield today and fired her up.
A few issues to work through. And it’s probably really simple but my brain is fogged from all the other faults this game has thrown at me today.

The small coil which opens the loop gate. I have voltage on the red wires lug but nothing on the brown grey wire.

All other coils work in test. Just this one.

It’s possible I’ve wired it wrong but surely the voltage would still be there?
It’s on Q44 which I haven’t checked yet. Again, would impact voltage at the lugs? I have no idea

Where do I start.
Thanks
Gaz

 

[Fantazia2]

You should have voltage on one side of the coil (red) the other side (broen grey) should get grounded by the transistor when the game triggers it.

I think you can test the coil by grounding the lug with the brown/grey wire to manually fire the coil, if that works the issue is likely on the board or wiring.

 

[Ashbo]

Hey folks.
This frickin Bally Corvette has fought me at every turn.
After 4 years, I reunited the cab and playfield today and fired her up.
A few issues to work through. And it’s probably really simple but my brain is fogged from all the other faults this game has thrown at me today.

The small coil which opens the loop gate. I have voltage on the red wires lug but nothing on the brown grey wire.

All other coils work in test. Just this one.

It’s possible I’ve wired it wrong but surely the voltage would still be there?
It’s on Q44 which I haven’t checked yet. Again, would impact voltage at the lugs? I have no idea

Where do I start.
Thanks
Gaz

View attachment 285293

Voltage will be on the red wire all the time, but only through the grey wire when the transistor switches to connect the grey to earth, so it may be the transistor or a connector / pin on the driver board.

Other wise it may be the coil, measure the resistance of the coil , if it’s zero it’s dead.

 

[Spandangler]

Thanks both. I’ll check all those things tomorrow.

I definitely had voltage on both lugs of the coils on others i checked. (Pop bumpers) another small gate coil.

 

[Fantazia2]

If you're testing both lugs to ground then I think yes you see voltage on both if the coils ok, one direct to the power source and the other going via the coil.

If you're not getting voltage on the other side of this coil like the others then sounds like it's a dead coil.

Im no expert though.

 

[Spandangler]

Thanks Chris. The gift that keeps on giving this machine!

 

[drhex]

With coil off you will have voltage at both lugs if the coil is ok. Coil on, voltage on the red lug, no voltage on controlled lug. Reason for this is no current through the coil when off so no voltage drop across it. Your coilisbroken, check if the thin coil wire is connected to both lugs. You may be able to fix it if it has come lose. Good chance the driveris broken and the coil is fried though.